Emily Dickinson Lexicon

DEL'TOID, a. [Gr. δελτα, the letter Δ, and ειδος, form.]

1. Resembling the Greek Δ, triangular; an epithet applied to a muscle of the shoulder which moves the arm forward, upward, and backward. – Coxe.
2. In botany, shaped somewhat like a delta or rhomb, having four angles, of which the lateral ones are less distant from the base than the others; as, a deltoid leaf. – Linnæus. Martyn. Trowel-shaped, having three angles, of which the terminal one is much further from the base than the lateral ones. – Smith.